This invention relates in general to vehicle drum brake assemblies and in particular to an improved mounting system for such a vehicle drum brake assembly.
Most vehicles are equipped with a brake system for slowing or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. The brake assemblies can be actuated by hydraulic, pneumatic, or mechanical pressure generated by an operator of the vehicle depressing a foot pedal, pulling a hand lever, and the like. The structure and operation of both drum brake assemblies and disc brake assemblies, as well as the actuators therefor, are well known in the art.
A typical drum brake assembly includes a backing plate which is secured to a fixed, non-rotatable component of the vehicle, such as the vehicle axle housing or steering knuckle, by a plurality of fasteners or bolts. Typically, four bolts extend through the backing plate to secure the backing plate to a flange of the axle housing. A pair of opposed arcuate brake shoes are supported on the backing plate for selective movement relative thereto. Each of the brake shoes has a friction pad secured thereto. The drum brake assembly further includes a cylindrical brake drum which is secured to the vehicle wheel for rotation therewith. The interior of the brake drum is hollow, defining an inner cylindrical braking surface. The brake drum is disposed adjacent to the backing plate such that the brake shoes extend within the inner cylindrical braking surface. To effect braking action, the brake shoes are moved outwardly apart from one another such that the friction pads frictionally engage the inner cylindrical braking surface of the brake drum. Such frictional engagement causes slowing or stopping of the rotational movement of the brake drum and, therefore, the wheel of the vehicle in a controlled manner.
One or more actuating mechanisms are provided in the drum brake assembly for selectively moving the brake shoes outwardly apart from one another into frictional engagement with the cylindrical braking surface of the brake drum. Usually, a hydraulically or pneumatically actuated service brake mechanism is provided for selectively actuating the drum brake assembly under normal operating conditions. Such a service brake mechanism can include a hydraulically actuated wheel cylinder having a pair of opposed pistons which abut and move the brake shoes apart from one another into frictional engagement with the cylindrical braking surface of the brake drum.
A mechanically actuated parking and emergency brake mechanism is also usually provided for selectively actuating the drum brake assembly. The parking and service brake mechanism can include an actuating lever pivotally supported on one of the brake shoes. The actuating lever is connected to a cable which, when pulled, moves the brake shoes apart from one another into frictional engagement with the cylindrical braking surface of the brake drum.
This invention relates to a vehicle drum brake assembly adapted to selectively frictionally engage a brake drum. The drum brake assembly includes a backing plate supported relative to a vehicle component and having at least three openings formed therethrough, at least one brake shoe supported on the backing plate for selective movement into frictional engagement with the brake drum, and a brake mechanism for selectively moving the brake shoe into frictional engagement with the brake drum. The drum brake assembly includes a pair of fasteners extending through two of the three openings provided in the backing plate to secure the backing plate to a fixed, non-rotatable component of the vehicle. The drum brake assembly further includes a member having a first portion operatively connected to the brake shoe and a second portion extending through the third of the three openings provided in the backing plate and secured to the fixed, non-rotatable component of the vehicle, wherein during application of the drum brake assembly the member is operative to transfer braking torque from the brake shoe to the non-rotatable component of the vehicle.
Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.